CN112751435B - Magnetic integrated eccentric magnetic pole structure of external rotor hub motor - Google Patents
Magnetic integrated eccentric magnetic pole structure of external rotor hub motor Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
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Abstract
The invention relates to a magnetic integrated eccentric magnetic pole structure of an outer rotor hub motor. The invention relates to the technical field of direct drive type in-wheel motors, and an eccentric magnetic pole structure comprises a permanent magnet main magnetic pole and a ferrite auxiliary magnetic pole; the permanent magnet main magnetic pole is used for generating air gap main magnetic flux and acts with a rotating magnetic field generated by the stator to generate torque to drive the vehicle hub to rotate; after the ferrite auxiliary magnetic pole is integrated with the permanent magnet main magnetic pole, the fluctuation of the air gap flux density is close to a sine wave, the harmonic content in the air gap flux density is reduced, and the torque pulsation is reduced. The invention reduces the use amount of the permanent magnet in the magnetic pole and reduces the cost of the motor on the premise of not reducing the output torque basically. Meanwhile, the permanent magnets are subjected to eccentric pole cutting through the ferrite auxiliary magnetic poles which are distributed in a stepped mode, the harmonic content in an air gap magnetic field is reduced, and the torque pulsation of the motor is restrained.
Description
Technical Field
The invention relates to the technical field of direct drive type hub motors, in particular to a magnetic integrated eccentric magnetic pole structure of an outer rotor hub motor.
Background
The increasing oil crisis, resource exhaustion and other problems cause the electric automobile to regain the attention of the world. As a core component of the electric automobile, the driving motor directly determines the driving performance and the production cost of the automobile, and plays a vital role in the popularization and development of the electric automobile. Have received considerable attention from various automobile manufacturers and research institutes. Compare in traditional PMSM, in-wheel motor drive system can be in the same place arresting gear and drive arrangement integration to reduced the motor volume, promoted power density, realized on-vehicle motor's miniaturization. Therefore, the hub motor has become a research focus of automobile manufacturers and research institutions at home and abroad.
The hub motor can be divided into a speed reduction driving hub motor and a direct driving hub motor. The direct-drive hub motor adopts an outer rotor structure, complex mechanical structures such as a speed reducer are omitted in the driving mode, application of auxiliary equipment is reduced, and cost failure rate of the electric automobile is greatly reduced. However, since the in-wheel motor needs to be directly installed in the wheel hub of the vehicle, the number of the vehicle-mounted motors is larger than that of the conventional vehicle using the permanent magnet synchronous motor. On the other hand, because the vehicle is directly driven by the rotor of the in-wheel motor, the output stability of the motor directly determines the driving comfort of the electric automobile. To sum up, the cost problem and the output stability problem are two main bottlenecks limiting the large-scale popularization of the hub motor.
In order to solve the problems of motor cost and torque ripple, research institutions at home and abroad carry out a great deal of research on the method. The document [ Luo Zhenghao, Jing founding soldier, Gao Xing, high rising, surface-mounted permanent magnet motor optimized design [ J ] micro special motor, 2018,46(10) ] proposes a sectional eccentric magnetic pole structure, and the adoption of a sectional Halbach array permanent magnet can effectively reduce air gap flux density harmonic and inhibit torque pulsation. However, the magnetic poles in the structure are composed of permanent magnets with different magnetizing directions, so that the permanent magnets are large in using amount and high in cost. The literature [ he zhou hong. bread type eccentric magnetic pole permanent magnet motor magnetic pole optimization design [ J ] micromotor, 2020,53(08):27-32 ] proposes a bread type magnetic core adopting an inverse cosine passive structure, which can effectively reduce torque pulsation by calculating the optimal eccentric distance, but the structure also has the defects of larger permanent magnet consumption and higher cost. Patent [ application No.: CNIO8347113A proposes a double-layer combined magnetic pole structure, which increases the amplitude of the fundamental magnetic field and reduces the harmonic content by using the combination of permanent magnets with different magnetizing directions and ferrite cores. But the double layer pole structure further increases the cost of the motor. Patent [ application No.: CNIO5449968A proposes a combined surface-mounted magnetic pole structure, which reduces the permanent magnet consumption and the cost by embedding ferrite in the permanent magnet. However, this structure cannot effectively reduce the air gap harmonic flux density, and therefore has a disadvantage of large torque ripple. In summary, the two main methods for reducing the cost and torque ripple of the motor are the integrated magnetic pole structure and the eccentric magnetic pole structure, however, in the existing research, the optimization of the magnetic pole structure only considers a single optimization target, so that the existing structure cannot meet the requirements of the hub motor on low cost and low torque ripple at the same time.
Disclosure of Invention
The invention reduces the use amount of the permanent magnet in the magnetic pole and reduces the cost of the motor on the premise of not reducing the output torque basically. Meanwhile, the permanent magnets are subjected to eccentric pole cutting through the ferrite auxiliary magnetic poles which are distributed in a stepped mode, the harmonic content in an air gap magnetic field is reduced, and the torque pulsation of the motor is restrained. On the other hand, compared with the traditional eccentric magnetic pole structure, the structure of the invention does not need to carry out eccentric treatment on the permanent magnet magnetic pole and the rotor core, thereby reducing the processing difficulty of the motor, and providing the following technical scheme:
a magnetic integrated eccentric magnetic pole structure of an outer rotor hub motor comprises a permanent magnet main magnetic pole and a ferrite auxiliary magnetic pole;
the permanent magnet main magnetic pole is used for generating air gap main magnetic flux and acts with a rotating magnetic field generated by the stator to generate torque to drive the vehicle hub to rotate;
after the ferrite auxiliary magnetic pole is integrated with the permanent magnet main magnetic pole, the fluctuation of the air gap flux density is close to a sine wave, the harmonic content in the air gap flux density is reduced, and the torque pulsation is reduced.
Preferably, the permanent magnet main pole is made of neodymium iron boron material, the permanent magnet main pole adopts a radial magnetizing mode, the lower surface of the permanent magnet main pole is of a smooth arc structure, and the radius is R in Center of circle is O 0 The angle corresponding to the magnetic pole is theta m ；
The upper surface of the main magnetic pole of the permanent magnet is in a stepped arc structure, the number of steps is 2m +1, wherein m is a positive integer; the upper surface and the lower surface of the single step structure are concentric circular arcs, and the height of the single step structure is h; all the ladder structures have the same height and the same corresponding angles, which are theta m /(2m+1)；
All corners of the ladder structure are positioned at the circle center and are O 1 Radius R out Above the arc of (1), wherein the center of the circle is O 0 And center O 1 The distance between is the eccentricity a.
Preferably, the main magnetic pole of the permanent magnet is equivalently processed eccentrically through a stepped circular arc structure; the ladder structure is in a symmetrical structure about the central axis of the magnetic pole of the permanent magnet, and the height of the ladder structure is gradually increased from the outer side to the central axis of the magnetic pole.
Preferably, as the number of steps 2m +1 is increased, the consistency of an air gap magnetic field generated by the main magnetic pole of the permanent magnet and a magnetic field generated by the magnetic pole of the permanent magnet after the eccentric pole cutting treatment is increased; the number of the steps is 2m +1, and the angle corresponding to the main pole of the permanent magnet is theta m Determine the smaller the number of poles of the in-wheel motor, theta m The larger m is increased in order to reduce harmonic components in the air-gap field generated by the main pole of the permanent magnet.
Preferably, by increasing the eccentricity a, the amplitude of the fundamental component in the air-gap magnetic field generated by the main magnetic pole of the permanent magnet is increased, the harmonic magnetic field content in the air-gap magnetic field is effectively reduced, and the torque ripple is suppressed.
Preferably, the ferrite auxiliary magnetic pole is made of soft magnetic ferrite, and the radius of the arc lower surface of the ferrite auxiliary magnetic pole is R in Center of circle is O 0 Corresponding to an angle of theta s (ii) a The upper part of the ferrite auxiliary magnetic pole is a step-shaped layered arc, and the number of steps is m + 1; the upper surface and the lower surface of each single step structure are concentric circular arcs, and the heights of all the step structures are h; the angle corresponding to the outer side step arc structure is theta s The corresponding angle of the inner side step arc structure is theta m V (2m + 1); the stepped structure of the ferrite auxiliary magnetic pole is complementary with the stepped structure of the permanent magnet main magnetic pole and is tightly meshed together.
Preferably, the ferrite auxiliary magnetic pole is engaged with the permanent magnet main magnetic pole and has a circular arc structure, and the radius of the lower surface of the circular arc is R in R of circular arc upper surface rotor Radius as center of circle is O 0 Corresponding to an angle of theta m +2θ s 。
Preferably, when
When the magnetic integrated eccentric magnetic pole structure is adopted, 3-order and 5-order harmonics are reduced to the maximum extent; when in use
And in the process, 7-order and 13-order harmonics are reduced to the maximum extent by the magnetic integrated eccentric magnetic pole structure.
Preferably, when
When the magnetic integrated type eccentric magnetic pole structure is used, 11 th harmonic, 13 th harmonic, 15 th harmonic, 17 th harmonic and 19 th harmonic are reduced to the maximum extent.
Preferably, when determining the corresponding angles of the permanent magnet main pole and the ferrite main pole, the theta shall be specifically designed according to the number of major harmonics in the air-gap magnetic field m And theta s The ratio of (a) to (b).
The invention has the following beneficial effects:
the invention integrates the advantages of the traditional combined magnetic pole structure and the eccentric magnetic pole structure, can simultaneously reduce the consumption of the permanent magnet in the motor and the harmonic content in the air gap magnetic field, and has the advantages of low cost and low torque pulsation. Compared with the traditional permanent magnet magnetic pole structure, the structure of the invention uses the ferrite to replace the permanent magnet magnetic pole by integrating the permanent magnet main magnetic pole and the ferrite auxiliary magnetic pole on the premise of not reducing the output torque basically, thereby reducing the use amount of the permanent magnet in the magnetic pole and reducing the cost of the motor. Meanwhile, the permanent magnets are subjected to eccentric pole cutting through the ferrite auxiliary magnetic poles which are distributed in a stepped mode, the harmonic content in an air gap magnetic field is reduced, and the torque pulsation of the motor is restrained. On the other hand, compared with the traditional eccentric magnetic pole structure, the structure of the invention does not need to carry out eccentric treatment on the permanent magnet magnetic pole and the rotor core, thereby reducing the processing difficulty of the motor.
Drawings
FIG. 1 is a schematic structural view of a magnetically integrated eccentric magnetic pole in-wheel motor according to the present invention;
FIG. 2 is a schematic diagram of a conventional in-wheel motor;
fig. 3 is a schematic structural view of the magnetic integrated eccentric magnetic pole hub motor according to the present invention;
FIG. 4 is a schematic diagram of a magnetic pole structure of a conventional eccentric pole-cutting machine;
fig. 5 is a schematic structural view of a conventional integrated magnetic pole;
fig. 6 is a comparison graph of air gap flux density waveforms of the magnetic integrated type eccentric magnetic pole hub motor and the conventional surface-mounted type hub motor.
Detailed Description
The present invention will be described in detail with reference to specific examples.
The first embodiment is as follows:
aiming at the traditional outer rotor surface-mounted hub motor, a ferrite material with low cost is used as an auxiliary magnetic pole to replace a permanent magnet material in the traditional magnetic pole, so that the use amount of a rare earth permanent magnet is reduced, and the purpose of reducing the cost is realized; the permanent magnet magnetic pole is designed into a stepped arc structure, and the permanent magnet magnetic pole is equivalently subjected to eccentric processing, so that an air gap magnetic field generated by the main magnetic pole of the magnet is basically consistent with a magnetic field generated by the permanent magnet magnetic pole subjected to eccentric pole cutting processing, the harmonic content in the air gap magnetic field is further weakened, and the purpose of inhibiting torque pulsation is achieved; meanwhile, because the remanence of the ferrite material is far lower than that of the rare earth permanent magnet material, the waveform of the air gap flux density can be closer to a sine wave through the integrated combination of the step-shaped permanent magnet main pole and the step-shaped ferrite auxiliary pole, and the output stability of the hub motor is further improved; in addition, the anti-demagnetization capability of the ferrite material is higher than that of the rare earth permanent magnet material, and after the ferrite material and the rare earth permanent magnet material are integrated, the local demagnetization risk of the original rare earth permanent magnet material can be greatly reduced, and the running reliability of the motor is improved; furthermore, the main magnetic pole structure of the stepped arc-shaped permanent magnet avoids eccentric pole cutting of the magnetic pole, the processing difficulty of the motor can be reduced, and meanwhile, the outer surface of the integrated rear eccentric magnetic pole mechanism is a smooth arc and can be well attached to the inner circle of the rotor core, so that the problem that the rotor core needs to be specially processed in the traditional eccentric magnetic pole hub motor is solved.
According to the drawings of fig. 1-6, the motor is installed in the hub of the electric automobile, and consists of five parts, namely a permanent magnet main magnetic pole 1, a ferrite auxiliary magnetic pole 2, a rotor core 3, a stator core 4 and a stator winding 5; the permanent magnet main magnetic pole structure is used for generating air gap main magnetic flux, and the ferrite auxiliary magnetic pole structure is used for reducing the harmonic content in air gap flux density after being integrated with the permanent magnet main magnetic pole, reducing torque pulsation, reducing the using amount of the permanent magnet and reducing the cost of the motor; the motor is of a direct-drive type outer rotor structure, and the rotating speed of the motor is the rotating speed of the wheels, so that the rotating speed is low, mechanical transmission is omitted, the dynamic response is quick, and the overall efficiency is further improved; the rotor iron core is in an arc-shaped structure, a silicon steel sheet structure is adopted, special processes such as sinusoidal pole cutting or eccentric pole cutting are not needed, and the processing difficulty is low; the stator core is also of a silicon steel sheet structure and is installed and fixed on the vehicle shaft; the stator winding is embedded in the slot of the stator core;
FIG. 2 is a schematic structural diagram of a conventional hub motor, in which a rotor is a circular arc permanent magnet magnetic pole, and since the conventional permanent magnet magnetic pole structure is not subjected to sinusoidal or eccentric pole cutting, the air gap flux density generated by a main magnetic pole is approximately distributed in the shape of steamed bread waves, and contains a large amount of harmonic components; during the rotation of the rotor, the existence of harmonic components in the air gap flux density can cause torque pulsation, so that the driving comfort of a vehicle is influenced;
compared with the traditional hub motor shown in the attached figure 2, the hub motor with the magnetic integrated eccentric magnetic pole structure uses a ferrite material with low cost as an auxiliary magnetic pole to replace a permanent magnet material in the traditional magnetic pole, so that the use amount of a rare earth permanent magnet is reduced, and the purpose of reducing the cost is realized; the permanent magnet magnetic pole is designed into a stepped arc structure, and the permanent magnet magnetic pole is equivalently subjected to eccentric processing, so that an air gap magnetic field generated by the main magnetic pole of the magnet is basically consistent with a magnetic field generated by the permanent magnet magnetic pole subjected to eccentric pole cutting processing, the harmonic content in the air gap magnetic field is further weakened, and the purpose of inhibiting torque pulsation is achieved; meanwhile, because the remanence of the ferrite material is far lower than that of the rare earth permanent magnet material, the waveform of the air gap flux density can be closer to a sine wave through the integrated combination of the step-shaped permanent magnet main pole and the step-shaped ferrite auxiliary pole, and the output stability of the hub motor is further improved; in addition, the anti-demagnetization capability of the ferrite material is stronger than that of the rare earth permanent magnet material, and after the ferrite material and the rare earth permanent magnet material are integrated, the local demagnetization risk of the original rare earth permanent magnet material can be greatly reduced, and the running reliability of the motor is improved; furthermore, the main magnetic pole structure of the stepped arc-shaped permanent magnet avoids eccentric pole cutting of the magnetic pole, the processing difficulty of the motor can be reduced, and meanwhile, the outer surface of the integrated rear eccentric magnetic pole mechanism is a smooth arc and can be well attached to the inner circle of the rotor core, so that the problem that the rotor core needs to be specially processed in the traditional eccentric magnetic pole hub motor is solved.
The magnetic integrated eccentric magnetic pole structure is shown in figure 3 and consists of two parts, wherein the first part is a permanent magnet main magnetic pole structure and is used for generating air gap main magnetic flux and generating torque to drive a vehicle hub to rotate under the action of a rotating magnetic field generated by a stator; the second part is a ferrite auxiliary magnetic pole structure and is used for enabling the air gap flux density fluctuation to be closer to a sine wave after being integrated with a permanent magnet main magnetic pole, reducing the harmonic content in the air gap flux density, reducing the torque pulsation, reducing the using amount of the permanent magnet and reducing the cost of the motor;
the main magnetic pole of the permanent magnet is made of neodymium iron boron material, adopts a radial magnetizing mode, and has a smooth arc structure on the lower surface and a radius of R in Center of circle is O 0 The angle corresponding to the magnetic pole is theta m (ii) a The upper surface is of a step circular arc structure, the number of steps is 2m +1, wherein m is a positive integer; the upper surface and the lower surface of the single step structure are concentric circular arcs, and the height of the single step structure is h; all the ladder structures have the same height and the same corresponding angles, which are theta m V (2m + 1); all corners of the ladder structure are positioned at the circle center and are O 1 Radius R out Above the arc of (1), wherein the center of the circle is O 0 And center O of circle 1 The distance between the two is eccentricity a; the main magnetic pole of the permanent magnet is equivalently eccentrically processed through a stepped arc-shaped structure; the ladder structure is in a symmetrical structure relative to the central axis of the magnetic pole of the permanent magnet, and the height of the ladder structure is gradually increased from the outer side to the central axis of the magnetic pole;
the ferrite auxiliary magnetic pole is made of soft magnetic ferrite, and the radius of the lower surface of the circular arc is R in Center of circle is O 0 Corresponding to an angle of theta s (ii) a The upper surface is a step-shaped layered arc, and the number of steps is m + 1; the upper and lower surfaces of the single step structure are concentricThe height of all the step structures is h; the angle corresponding to the outer side step arc structure is theta s The inner side of the stepped arc structure has a corresponding angle theta m /(2m + 1); the stepped structure of the ferrite auxiliary magnetic pole is complementary with the stepped structure of the permanent magnet main magnetic pole and can be tightly meshed together; furthermore, after the ferrite auxiliary magnetic pole is meshed with the permanent magnet main magnetic pole, the ferrite auxiliary magnetic pole is in a circular arc structure, and the radius of the lower surface of the circular arc is R in R of circular arc upper surface rotor Radius as center of circle as O 0 Corresponding to an angle theta m +2θ s ；
FIG. 4 is a schematic structural diagram of a magnetic pole structure of a conventional eccentric pole-cutting machine; the decoupling strand can effectively reduce air gap flux density harmonic waves and inhibit torque pulsation by cutting the main pole of the permanent magnet; however, the permanent magnet in the structure has larger consumption and higher cost; meanwhile, the rotor core needs to be processed by pole cutting according to the shape of the main magnetic pole, so that the processing difficulty is high;
fig. 5 is a schematic structural diagram of a conventional integrated magnetic pole, in which ferrite material is used to replace a part of rare earth permanent magnetic material, and the ferrite is placed on both sides of the rare earth permanent magnetic material to reduce the cost; however, the structure does not specially design the main magnetic pole of the permanent magnet, so that the harmonic content in the air gap flux density is higher, and the torque pulsation of the motor is larger;
FIG. 6 is a comparison graph of air gap flux density waveforms between the magnetic integrated eccentric magnetic pole hub motor of the present invention and the conventional surface-mounted hub motor shown in FIG. 2; the permanent magnets can be clamped out from the figure, and the permanent magnets are subjected to eccentric pole cutting through the ferrite auxiliary magnetic poles which are distributed in a stepped mode, so that the harmonic content in an air gap magnetic field is reduced, and the torque pulsation of the motor is restrained;
detailed description of the invention
This embodiment mode is a further description of the first embodiment mode;
in the permanent magnet main pole, the larger the step number 2m +1 is, the higher the consistency of an air gap magnetic field generated by the permanent magnet main pole and a magnetic field generated by the permanent magnet magnetic pole after eccentric pole cutting treatment is, but m is increasedThe use amount of the permanent magnet and the processing difficulty of the magnetic pole can be increased; the number of the steps is 2m +1, and the angle corresponding to the main pole of the permanent magnet is theta m Determining the smaller the number of poles of the in-wheel motor, theta m The larger the size is, the larger m is needed to reduce harmonic components in an air gap magnetic field generated by the main magnetic pole of the permanent magnet;
furthermore, the amplitude of the fundamental component in the air gap magnetic field generated by the permanent magnet main pole can be increased by increasing the eccentricity a, but the amplitude of the harmonic component is not influenced; therefore, the harmonic magnetic field content in the air gap magnetic field can be effectively reduced by increasing the eccentricity a, and the torque pulsation is inhibited; however, the eccentricity a can increase the radius of the rotor and the using amount of the permanent magnet at the same time, thereby increasing the volume and cost of the motor; the eccentricity a is comprehensively designed according to the radius of a motor rotor, cost and output torque fluctuation rate;
detailed description of the invention
This embodiment mode is a further description of the first embodiment mode;
in the magnetic integrated eccentric magnetic pole structure, the angle theta corresponding to the main magnetic pole of the permanent magnet m The angle corresponding to the outer side step arc structure in the ferrite auxiliary magnetic pole is theta s The ratio of (A) to (B) satisfies:
when in use
In the process, the magnetic integrated eccentric magnetic pole structure can reduce 3-order and 5-order harmonics to the maximum extent, and has no inhibiting effect on 11-order, 13-order and 15-order harmonics; when in use
In the process, the magnetic integrated eccentric magnetic pole structure can reduce 7-order and 13-order harmonics to the maximum extent, and has no inhibiting effect on 15-order and 17-order harmonics; when in use
In the invention, the magnetic integrated eccentric magnetic pole structure can reduce 11 th harmonic, 13 th harmonic, 15 th harmonic, 17 th harmonic and 19 th harmonic to the maximum extent, but can increase 3 rd harmonicWave, 5 th harmonic, and 7 th harmonic;
furthermore, when designing the corresponding angle between the permanent magnet main pole and the ferrite main pole, the theta should be specifically designed according to the number of the major harmonics in the air gap magnetic field m And theta s The ratio of (A) to (B);
the above description is only a preferred embodiment of the magnetic integrated eccentric magnetic pole structure of the external rotor in-wheel motor, and the protection range of the magnetic integrated eccentric magnetic pole structure of the external rotor in-wheel motor is not limited to the above embodiments, and all technical solutions belonging to the idea belong to the protection range of the present invention. It should be noted that modifications and variations which do not depart from the gist of the invention will be those skilled in the art to which the invention pertains and which are intended to be within the scope of the invention.
Claims (7)
1. The utility model provides an eccentric magnetic pole structure of magnetism integrated form of external rotor in-wheel motor which characterized by: the eccentric magnetic pole structure comprises a permanent magnet main magnetic pole and a ferrite auxiliary magnetic pole;
the permanent magnet main magnetic pole is used for generating air gap main magnetic flux and acting with a rotating magnetic field generated by the stator to generate torque to drive the vehicle hub to rotate;
the ferrite auxiliary magnetic pole is used for enabling the air gap flux density fluctuation to be close to a sine wave after being integrated with the permanent magnet main magnetic pole, reducing the harmonic content in the air gap flux density and reducing the torque pulsation;
the permanent magnet main pole is made of neodymium iron boron material and adopts a radial magnetizing mode, the lower surface of the permanent magnet main pole is of a smooth arc structure, and the radius of the lower surface is R in Center of circle is O 0 The angle corresponding to the main magnetic pole of the permanent magnet is theta m ；
The upper surface of the main magnetic pole of the permanent magnet is in a stepped arc structure, the number of steps is 2m +1, wherein m is a positive integer; the upper surface and the lower surface of the single step structure are concentric circular arc shapes, and the height is h; all the ladder structures have the same height and the same corresponding angles, which are theta m /(2m+1)；
The corners of all the ladder structures are positioned at the circle center and are O 1 Radius R out Above the arc of (1), wherein the center of the circle is O 0 And center O 1 The distance between the two is eccentricity a;
the main magnetic pole of the permanent magnet is equivalently eccentrically processed through a stepped arc-shaped structure; the ladder structure is in a symmetrical structure relative to the central axis of the main magnetic pole of the permanent magnet, and the height of the ladder structure increases from the outer side to the central axis of the magnetic pole;
the ferrite auxiliary magnetic pole is made of soft magnetic ferrite, the radius of the arc lower surface of the ferrite auxiliary magnetic pole is Rin, the circle center is O0, and the corresponding angle is theta s; the upper part of the ferrite auxiliary magnetic pole is a step-shaped layered arc, and the number of steps is m + 1; the upper surface and the lower surface of each single step structure are concentric circular arcs, and the heights of all the step structures are h; the angle corresponding to the outer stepped arc structure is theta s, and the angle corresponding to the inner stepped arc structure is theta m /(2m + 1); the stepped structure of the ferrite auxiliary magnetic pole is complementary with the stepped structure of the permanent magnet main magnetic pole and is tightly meshed together, and the two ferrite auxiliary magnetic poles are respectively arranged on two sides of the permanent magnet main magnetic pole.
2. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor in claim 1, wherein: with the increase of the number of steps of 2m +1, the consistency of an air gap magnetic field generated by the main magnetic pole of the permanent magnet and a magnetic field generated by the magnetic pole of the permanent magnet after eccentric pole cutting treatment is increased; the number of steps 2m +1 is the angle theta corresponding to the main pole of the permanent magnet m Determining the smaller the number of poles of the in-wheel motor, theta m The larger m is, in order to reduce harmonic components in the air-gap magnetic field generated by the main pole of the permanent magnet, the larger m is.
3. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor as claimed in claim 2, wherein: by increasing the eccentricity a, the amplitude of the fundamental component in the air-gap magnetic field generated by the main magnetic pole of the permanent magnet is increased, the harmonic magnetic field content in the air-gap magnetic field is effectively reduced, and the torque pulsation is inhibited.
4. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor in claim 1, wherein:
the ferrite auxiliary magnetic pole is engaged with the permanent magnet main magnetic pole and has a circular arc structure, and the radius of the circular arc lower surface is R in Radius of the circular arc upper surface is R rotor Center of circle is O 0 Corresponding to an angle theta m +2θ s 。
5. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor as claimed in claim 4, wherein: when the temperature is higher than the set temperature
When the magnetic integrated eccentric magnetic pole structure is used, 3-order and 5-order harmonics are reduced to the maximum extent; when in use
And in the process, 7-order and 13-order harmonics are reduced to the maximum extent by the magnetic integrated eccentric magnetic pole structure.
6. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor in claim 3, wherein: when in use
When the magnetic integrated type eccentric magnetic pole structure is used, 11 th harmonic, 13 th harmonic, 15 th harmonic, 17 th harmonic and 19 th harmonic are reduced to the maximum extent.
7. The magnetic integrated eccentric magnetic pole structure of the external rotor hub motor as claimed in claim 6, wherein: when determining the corresponding angle of the permanent magnet main pole and the ferrite main pole, the theta is specifically designed according to the number of the main harmonic in the air gap magnetic field m And theta s The ratio of (a) to (b).
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| CN116914964B (en) * | 2023-07-13 | 2024-04-09 | 清华大学 | Hub motor and permanent magnet structure thereof |
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